Fuel system with means to compensate for variations in liquid head due to accelerations acting on the fuel system



sfipt. 17, 1957 COOK I FUEL. SYSTEM WITH MEANS TO COMPENSATEFOR VARIATIONS IN LIQUID HEAD DUE TO AC ERATIONS ACTING ON THE FUEL. TEM

' 5 Sheets-Sheet 1 Filedjlarch 51 1952 MIIIEII TOH [IV/W 000K @WMJ WW Sept. 17, 1957 300 2,806,354

FUEL SYSTEM WITH MEANS TO COMPENSATE FOR VARIATIONS IN LIQUID HEADDUE TO ACCELERATIONS ACTING ON THE FUEL SYSTEM I Filed March 51,1952 5 Sheets-Shet 2 17 19 5% 55% as W/ j 51d\ \Qi 52 4 I I "4* 6 I z l j 5% p Z 55 I j 5i 52 fifl 19 1729.6. 555 52 35 V m 500 0 I ii/ITO HENRY 000K P 7, 1957 H. cooK 2,806,354. FUEL SYSTEM WITH MEANSTO COMPENSATE FOR VARIATIONS IN LIQUID HEAD DUE TO ACCELERATIONS ACTING ON THE FUEL SYSTEM Fi1ed Ma.rch 31, 1952 5 Sheets-Sheet 3 IIWENTOR Sgpt. 17, 1957 2,806,354

H cooK FUEL. SYSTEM WITH MEANS TO COMPENSATE FOR VARIATIONS IN LIQUID HEAD DUE TO ACCELERATIONS ACTING ON THE FUEL SYSTEM FiledMaI-ch s1 1952 5 Sheets-Sheet 4 Mum/TM.

H. CO FUEL SYSTEM WITH MEANS TO COMPENSATE FOR VARIATIONS Sept. 17, 1957 0K 2,806,354

IN LIQUID HEAD DUE TO ACCELERATIONS ACTING ON THE FUEL SYSTEM Filed flarch 31, 1952 5 Sheets-Sheet 5 imam/r02 ye/var 60oz United States Patent FUEL SYSTEM WITH MEANS T0 COMPENSATE FOR VARIATIONS IN LIQUID HEAD DUE T6 @ECELERATIONS AQTENG ON THE FUEL SYS- Henry Cook, Derby, England, assignor to Rolls-Royce Limited, Derby, England, a British company Application March 31, 1952, Serial No. 279,655 Claims priority, application Great Britain April 5, H51

12 Claims. (Cl. 60-39.36) V This invention relates to liquid-flow systems of the kind (hereinafter referred to as gravity-sensitive liquid flow systems) comprising a pressure source of liquid, and a plurality of liquid-flow conduits having restricted outlets, which conduits are connected to said source to receive liquid therefrom and are so'disposed at levels in relation to one another that the liquid pressures controlling the flows in the conduits are different due to the different liquid heads to which they are subjected.

One well-known form of gravity-sensitive liquid-flow system is a gas-turbine engine fuel system, which comprises as the pressure source a manifold extending around the engine and as the liquid-flow conduits fuel pipes leading from the manifold at points around it to the fuel injection devices by which fuel is fed to the engine combustion equipment. Such a fuel system, Whether the engine is used as :a ground power-plant .or as an aircraft power plant, is subject to the disadvantage that the flows through the fuel pipes leading from the manifold differ substantially at low fuel source pressures due to the differences between the liquid pressures at the inlets to the fuel pipes connected to the lowermost portions of the manifold and at the inlets to the fuel pipes connected tothe uppermost portions of the manifold. The pressure differences are due to the different heights of fuel above the inlets to the different fuel pipes and, in many modern gas-turbine engines, may be of the order of 1 lb./ sq. in. on the ground and in level flight between the uppermost and the lowermost inlets. The differences may be substantially greater during manoeuvring of, for example, an aircraft in which the engine is installed, being increased in proportion to the acceleration imposed on the fuel system.

The present invention has for an object to provide means to avoid the disadvantages arising from the differences in liquid heads.

According to the present invention, there is provided a gravity-sensitive liquid-flow system, wherein each of a plurality of the liquid-flow conduits has located in it a valve loaded to oppose the flow through the conduit, and wherein the loads on the valves are individually adjusted to compensate for the differences in the liquid heads.

Thus, for instance, in a fuel system employing kerosene as a fuel, the valve in a conduit 3 ft. below a second conduit will be loaded to open at a pressure upstream of the valve about 1 lb./sq. in. higher than the pressure at the inlet to the second conduit, so that in this case the pressure downstream of the valve will be substantially equal to that in the'second conduit.

In one embodiment, suitable for stationary gravitysensitive liquid-flow systems, for instance fuel systems of stationary power plants, the valves may be spring-loaded and the spring-loadings may be adjusted to compensate for the differences in the liquid heads. Such an arrange ment is, however, unsuitable for use in, say, fuel systems of aircraft power plants since during manoeuvring of the aircraft the vertical acceleration acting on the fuel system may be greatly increased,

According to an important feature of this invention, therefore, each valve is of a construction by which automatic compensation is obtained for variations in the liquid head due to variations in the acceleration causing the liquid head, the valve comprising a weight arranged to be displaceable in 'a valve body in the direction of the acceleration which causes the differences in the liquid heads required to be compensated, and to co-operate with an inlet orifice in the valve body to oppose flow therethrough, the weight having its mass per unit area of the inlet orifice selected to give the desired liquid head compensation. If the acceleration is normal gravitational acceleration g or negative "g the weight will be displaceable vertically.

Thus for instance, if M is the mass of the weight, and A is the effective orifice area, then under stationary conditions the load opposing opening of the valve is where p is the liquid density, It will be clear that if the acceleration affecting the liquid head is, due to manoeuvre, say 4g then the new liquid head p is given by the equation M I P Q-Z Q and the effective load L due to the weight is given by per unit area of orifice, so that the increase in liquid pressure due to the increased acceleration is compensated automatically.

The weight will normally 'be arranged so that whatever its position it does not obstruct the valve outlet orifice. For instance, if the outlet orifice is at the opposite end of the valve body from the inlet orifice, there may be provided a bridge piece to limit the displacement of the weight towards the outlet orifice.

It will be appreciated that aircraft power plant fuel systems are not only required to operate under positive g conditions, that is, under conditions in which the acceleration affecting the liquid head acts vertically downwards with respect to the power plant, but are also required to operate under negative "g conditions in which the acceleration acts vertically upwards.

According to yet another important feature of this invention, there is provided in each flow conduit two flow control valves, each valve comprising a valve chamber having an inlet orifice, and a weight displaceable in the chamber to co-operate with and to control the flow through the inlet orifice, which valves are arranged so that under positive g conditions one valve compensates for the differences in liquid head, and under negative g conditions the other valve compensates for differences in the liquid head. Thus said one valve will have its inlet orifice at its lower end and said other valve will be reversed and have its inlet orifice at its upper end; moreover, the valve making the greatest compensation for positive g will have associated with it in its flow conduit the valve making the least compensation for negative g. The valves are preferably in flow series, and provision will be made so that the outlet orifices of both valves are unobstructed at all times. The valves may,

engine, the uppermost fuel pipe may be designatedthe compensation and master pipe in respect of positive g may have no valve, while the remaining pipes may-be fitted with compensating valve arrangements for accommodating the differences in fuel pressures at the inlets. to the remaining pipes with respect to the fuel pressure in the master pipe. In a similar manner the lowermost fuel pipe may be designated the master pipe in respect of negative g compensation, and the remaining pipes fitted with negative g compensating valves.

It is preferred however, in order that the valves may be of convenient dimensions, to provide a. compensating valve arrangement in each pipe and to vary the mass of the weight (or the spring load in the case of the embodiment suitable for stationary fuel systems) to provide the compensation as between the different pipes; thus in a preferred arrangement the mass of the weights of those valves compensating for positive .g conditions may be chosen, in relation to the areas of the respective inlet orifices, so that the pressure drop through the uppermost valve is, say, lbs/sq. in., that through the lowermost valve is 11 lbs/sq. in. and that through a valve at intermediate height 10.5 lbs/sq. in. under stationary conditions. The area of the inlet orifice may also be varied, if desired, in order to effect the compensation.

When the liquid flow conduits lead from circumferentially spaced points around an annular manifold automatic compensation for variations in fuel head caused by acceleration components parallel to the plane of the manifold may also be achieved using weights having equal masses per unit orifice area,v and according to an important feature of this invention each valve may comprise a valve body having an inlet orifice connected to said manifold, a weight to co-operate with said inlet orifice to restrict liquid flow through the inlet orifice from said manifold, said weight being displaceable within the valve body away from the inlet orifice in a direction radially inwards of the annular manifold, and a spring preloading the weight in a direction to close the inlet orifice, the weights in all the valves having each a mass (m)- per unit area of the corresponding inlet orifice given by m: pg

where p is the density of the liquid and his the diameter of the annular manifold, and the spring loadings per unit orifice area on the weights in all the valves being equal. Preferably the weights are all equal in mass, the orifices equal in area and the springs equal in loading. With such an arrangement, variations in fuel head due to any acceleration component parallel to the plane of the manifold will be compensated, and it will be appreciated that any component normal to this plane will have no effect on the fuel head.

Some embodiments of this invention will now be described by way of example, the description making reference to the accompanying drawings, in which Figure 1 is a diagrammatic section through a gasturbine engine with means to supply fuel thereto,

Figure 2 illustrates a first embodiment of valve for use in accordance with this invention,

Figure 3 is a section on the line 33 of Figure 2,

Figure 4 illustrates a second embodiment of valve for use in accordance with this invention,

Figure 5 is a view corresponding to Figure 4 of a third embodiment of valve,

Figure 6 is a section on the line 6-6 of Figure 5,

Figure 7 is an axial section through part of a gasturbine engine and illustrating yet another embodiment of valve for use in accordance with this invention,

Figure 7A is an enlarged view of part of Figure 7,

Figure 8 is a section on the line 88 of Figu-ref7,

Figure 9 is a view corresponding to Figure 7 showing yet another embodiment of valve suitable for usewith this invention,

Figure 10 is a section on the line 10-10 of Figure 9, and

Figure 11 illustrates yet another embodiment.

Referring first to Figure 1, there is illustrated in diagram form a section at right angles to the axis of a gasturbine engine through the engine adjacent the inlet end of the combustion equipment of the engine. In this figure reference numeral 10 indicates a driving shaft normally provided to extend between a compressor and a coaxial driving turbine. The shaft 10 extends through the combustion equipment of the engine which comprises in the form illustrated a number of separate combustion chambers, indicated by reference numerals 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h, although it will be understood that'if desired the combustion equipment may be of the completely annular kind. Each combustion chamber is shown to be fitted with a single fuel injection device 12 and the fuel injection devices are supplied with fuel from a manifold 13 by individual fuel supply pipes 14a, 14b, 14c, 14d, 14c, 14 14g, 1411. The manifold is annular in form and encircles the engine and the fuel supply pipes 14a 14h are connected to the manifold 13 at circumferentially spaced points around the manifold, conveniently through unions 15a, 15b, 15c, 15d, 15e, 15f, 15g, 15h. A similar fuel supply arrangement will be employed when instead of the combustion chambers 11a 11h, a completely annular combustion chamber is employed.

If the fuel being supplied to the fuel injection devices 12 is kerosene and the manifold has a diameter of about 3 feet, thenif the unions 15a 15h are simple pipe connections the fuel pressure within the pipes 14a 14h will differ, the pressure in the pipe 14a being the lowest and the pressure in the pipe 14c being the highest and being about 1 lb./sq. in. greater than the pressure in the pipe 14a under normal stationary conditions. The pressures in the pipes 14h and 14b will be the same since their corresponding-unions 15b and 15h are level and similarly the pressures in pipes and 14g will be equal and the pressures in pipes 14d and 14f will be equal, the pressures in these pipes being intermediate the pressures in the pipes 14a and 14e.

This invention provides means whereby this difference in liquid pressures in the pipes 14a 14h may be compensated.

Referring now to Figures 2 and 3, there is illustrated one suitable form for the unions 15a 15h whereby the compensation may be obtained. Each union has a pair of sockets 16 into which the pipe sections 17 forming the manifold 13 are inserted, and a duct 18 intercom necting the sockets 16. The manifold 13 is thus formed from a number of sections of pipes 17 and the ducts 18 in the various unions 15a 15h. A branch duct 19 leads off from the duct 18 to the inlet port 20 of a valve body 21 formed in one piece with the union 15.

' The inlet port 20 leads to a cylindrical chamber 21a, arranged with its axis vertical when it is desired to compensate for differences in fuel heads due to vertical accelerations, and the operative element of the valve is formed by a cylindrical weight 22 slidable within the chamber 21617 The weight 22 co-openates with the port 20 to restrict the flow of fuel through the port 20 into the chamber 21a and the weight 22 is formed in its surface with a number of grooves 23; say four grooves, which together afford a passage connecting the inlet end of the chamber 21a with an enlarged outlet space 21b. An outlet socket 210 communicates with the enlarged outlet space 211) and receives an end of the appropriate fuel supply pipe 14a 14h.

The restriction afforded by the weight upon the flow of fuel from the manifold to the fuel supply pipe is given by the expression Where M is the mass of the weight 22. A is the elfective area of the orifice 20 and g is gravitational acceleration. Thus there will be in normal operation of the fuel system a drop in pressure across the valve given by the above expression.

In accordance with this invention, each of the unions 15a 15h is formed with a valve unit as just described and the masses of the Weights 22, or the effective areas of the ports 20 or both the weights and the ports will be adjusted to compensate for the difference in fuel pressure existing in the manifold adjacent the corresponding union 15a 15h due to the height of liquid above it. Thus, for instance, if the diameter of the manifold is h and p is the density of the liquid fuel, then the difference m per unit of orifice area in the masses of the weights 22 for the highest union 15a and the lowest union 15e to compensate for the increased pressure at the union 152, will be given by the expression m= h. The corresponding dilferences in the masses of the weights 22 for the other unions will in the same way be directly proportional to the difiTerences in their vertical heights. It will be clear that the lower is the union the higher is the mass of its weight 22 so that the greater is the pressure drop across the valve in the union.

Referring now to Figure 4, there is illustrated an arrangement which is similar to that just described but which enables compensation to be effected not only for positive acceleration but also for negative g acceleration.

In this arrangement each union 15 comprises in flow series a first valve which compensates for positive g and a second valve which compensates for negative g. The first valve comprises as in the previously described arrangement an inlet port controlled by a weight 22 with surface grooves 23 and an enlarged outlet space 21b. The outlet from the space 21b in this case communicates with the inlet port 24 of the second valve which inlet port 24 leads to a cylindrical chamber 25 having a weight 26 slidable within it. The weight 26 has surface grooves 27 which provide a connection between the inlet port 24 and an enlarged outlet space 28 from which an outlet port 29 leads to the corresponding fuel pipe 14. It will be seen that the axes of the two cylindrical chambers 21a and 25 are both vertical and that whilst the inlet port 20 of the chamber 21a is at the lower end of the chamber, the inlet port 24 is at the upper end of its chamber 25.

In operation under positive g conditions the valve weight 22 co-operates with its port 20 to control the flow through the valve arrangement, the weight 26 being in the position shown and inoperative. Under negative g conditions the weight 26 moves to the chain line position in which it co-operates with port 24 to control the flow through the valve arrangement and the valve weight 22 moves out of co-operation with its inlet port 20 and provides a free passage for the fuel from the manifold to the inlet port 24.

It will be clear that when the fuel system is operating under negative g conditions the pressure at union 15a becomes higher than the pressure at the union 15e, and the union 15a thus becomes effectively the lowermost union and the union 15a becomes effectively the uppermost union, the valve weight 27 for the union 15a will exceed the valve weight 27 for the union 15 by an amount given by the expression m= h.

Instead of arranging the two valve chambers in flow series between the duct and the fuel pipe, the two valve chambers may be connected in parallel and in this case the valve weights and the outlet ports from the outlet spaces will be arranged so that in the inoperative position of each valve, the weight closes off the outlet port from the outlet space. One such arrangement of the valve chambers, valve weights and outlet ports is shown in Figures 5 and 6.

In this arrangement, each valve comprises a weight 50 slidable in a chamber 51 having an inlet orifice 5101 at its one end. The weight 50 has axial grooves 52 cut in its surface to provide communication between the inlet orifice 51a and an outlet space 53 which is enlarged compared with the chamber 51. The outlet space 53 has in its wall facing the cylinder a land 53a which limits the movement of the weight 50 away from the inlet orifice 51a, and in its side walls a pair of outlet ports 53b which, when the weight 50 is operative to restrict flow through the inlet orifice 51a, are open to the outlet space 53, and which, when the weight 50 is inoperative and against the land 53a, are closed off from the space 53. In the arrangement illustrated, the outlet ports 53b are formed in flats on the walls of the space 53 and the weight 50 is formed with corresponding flats 50a. The use of twin outlet ports 53]; one on each side of the weight 50 ensures that the fluid pressure loads on the weight are balanced.

In the drawings, the positive g weight 50 (the right hand weight as seen in the drawings) is shown in the operative position and the negative g weight is shown in the inoperative position.

The inlet orifices 51a of the two chambers are both open to the manifold duct 18 through branch duct 19, and the outlet ports 53]) of both chambers 51 are in direct communication through ducts 54 with the fuel pipe 14 leading to fuel injection device.

It will be seen that, as in the arrangement of Figure 4, the positive g valve has its inlet orifice 5111 at the lower end of its chamber and negative g valve has its inlet orifice at the upper end of its chamber.

The mass of the weights 50 will be selected in the same way as is described for Figure 4.

It will be appreciated that by mounting the valves vertically as in the arrangements just described, the fuel pressures in the fuel supply pipes 14a 14h are compensated not only for acceleration due to gravitational force but also for any other accelerations or acceleration components due for example to the manoeuvring of an aircraft in which the fuel system is installed, in the direction of the vertical axis of the aircraft.

Referring now to Figlres 7, 7A and 8, there is illustrated another arrangement by which compensation may be had for variations in liquid head, and which auto matically compensates for variations in the effective g due, for instance, to manoeuvring of an aircraft in which the arrangement is employed.

In the drawings, the combustion equipment comprises an annular outer air casing wall 30 and an inner air casing wall 31 and between them inner and outer flame tube walls 32, 33. The air casing walls 30, 31 are connected with the delivery of a compressor 34 thereby to be supplied with compressed air, part of which flows directly into the space between the flame tube walls and the remainder of which flows into the space between the flame tube Walls 32, 33 and the adjacent air casing walls 31, 30 respectively.

Fuel is fed into the combustion equipment by a fuel supply arrangement similar to that indicated in Figure 1, there being a fuel supply manifold 35 and a plurality of fuel injection devices 36 each fed through an associated supply conduit 37 connected to the manifold by a union 38.

Each union 38 comprises a valve body 39 having an inlet port 40 flow through which is controlled by a valve member 41 slidable in the valve body 39 under the loading of a spring 42 which tends to close the valve member 41 on to theport 40. The port 40 gives access to an outlet space 43 communicating with the bore 37a of the conduit 37.

The valve bodies 39 are all arranged so that their directions 39a in which the valve members 41 slide intersect on the axis of the engine, i. e. the directions 39a are radial to the annular manifold 35.

The springs 42 are arranged to pre-load their associated valve members 41 to the same extent and the orifices are made of equal area (A). Further the valve members 41 are all of the same mass (M) which has a value such that the mass (111) per unit orifice area is given by the expression where =angle between the direction 39a and the vertical, p is the fuel density, h is the diameter of the manifold.

If the pre-loading afforded by the spring is S per unit orifice area, then the pressure drop across any valve is Smg cos 9. The difference between the pressure drops across valves at the lowermost and uppermost points of the manifold is 5) g) =p that is the difference in pressure drops equals the difference in fuel heads at the top and bottom of the manifold.

Referring now to Figures 9 and 10, there is illustrated an arrangement similar to Figures 7 and 8, but in which each union 38 is associated with two fuel injectors 136. Each union has as before a valve body 39 with an inlet 40 and an outlet space 43 and valve member 41 loaded by a spring 42. In this construction, however, the space 43 communicates with symmetrically-disposed branch conduits 137 each leading to one of the pair of associated fuel injectors 136. V

In yet another arrangement in accordance with the invention the two valve chambers in the union body are connected in parallel as in the arrangement shown in Fig. 5, but in this arrangement (Figure 11) there is a single valve weight 60. The chambers 61 are preferably arranged to be coaxial, the weight 60 being formed of two generally cylindrical portions 60a, 60b, one in each chamber 61 and co-operating with the respective inlet orifices 61a, 61b, and an intermediate portion 60c of smaller diameter extending through the two inlet orifices 61a, 61b. The inlet duct 19 will thus be of T-shape, two arms of the T affording annular ducts 19a, 19b surrounding and coaxial with the intermediate portion 600 of the weight 60 and leading to the orifices 61a, 61b, the third arm 19c eing in connection with the manifold 18. The outlet ports will be similar to the arrangement shown in Fig. 5 and will be arranged to be closed off by the cylindrical portion of the weight not operative at the time to restrict the flow through the inlet port.

In this arrangement the valve chambers may be arranged so that the weights slide in directions radial to the manifold, and in this case, since the mass of the weight co-operating with the two orifices in each union is a constant, the area of the radially outer orifice will be larger than the area of the radially inner orifice of each union. Conveniently the mass of each of the Weights will be the same, the area of the radially-outer orifices will be the same, and the areaof the radially-inner orifices will be the same, in which case if a is the area of a radially inner orifice, and A the area of a radially outer orifice,

h the diameter of the manifold.

I claim: l, A fuel system for a gas turbine power plant having a plurality of fuel nozzles at different vertical locations With respect to the power plant axis, and a valve associated with each nozzle for compensating for a difference in pressure head at the nozzles, each valve having a pas sage for the flow of fuel therethrough, a movable closure interposed in the passage and restricting fuel flow, and a seat for the closure defined by the passage walls, fuel flow through each valve being regulated by individually selecting the weight of each closure so as to equalize flow from the nozzles, said closure decreasing in weight as vertical height increases.

2. In a gas turbine power plant having a combustion section, a plurality of fuel nozzles mounted at different vertical locations within the combustion section, a source of fuel and at least one manifold connecting said fuel source and said nozzles; a pressure head compensating valve associated with each of said nozzles, each of said valves having a passage for the flow of fuel therethrough, a movable closure interposed in the passage and restricting fuel flow, a seat for the closure defined by the passage walls, the closure and seat being positioned so that gravity will have a maximum effect in seating the closure, the weight of each closure being individually selected and decreasing as vertical height increases so as to equalize fuel flow from the nozzles.

3. In a gas turbine power plant having a combustion section, a plurality of fuel nozzles mounted at different vertical locations within the combustion section, a source of fuel and at least one manifold connecting said fuel source and said nozzles; a pressure head compensating valve located between said manifold and each of said nozzles, each of said valves having passages for the flow of fuel therethrough, a weighted valve element interposed in the passages for restricting fuel flow through the valve, one of the passages having walls forming a seat for the valve element, the valve element being free to move away from the seat to increase fuel flow through the valve, the weight of the valve element in each valve being a function of the vertical location of the valve with respect to the other valves and decreasing as vertical height increases so as to equalize fuel flow from the nozzles, each valve being positioned so that gravity will exert a maximum force in seating the valve element during normal operation of the power plant.

4. In a gas turbine power plant having a combustion section, a plurality of fuel nozzles mounted at different vertical locations within the combustion section, a source of fuel and a manifold connecting said source and said nozzles; a pressure head compensating valve located between said manifold and each of said nozzles, each of said valves having an inlet and an outlet for the flow of fuel therethrough, an intermediate passage between said inlet and said outlet, the walls of the intermediatepassage defining a seat, a movable valve element adapted to be positioned on said seat and for restricting fuel flow through said intermediate passage and seat, the diameter of the valve element being'substantially larger than the diameter of the seat, a chamber surrounding said valve element and defining the path of motion of the valve element, the weight of the valve element in each valve being a function of the vertical location of the valve with respect to the other valves and decreasing'as vertical height increases so as to equalize fuel flow from the nozzles, each valve being positioned so that gravity will exert the maximum force in seating the valve element during normal operation of the power plant.

5. A fuel system comprising a fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors at locations spaced'apart in the direction of acceleration to which the system is subjected, a plurality of conduits connected to said manifold and leading to said injectors, each conduit having an upstream part having its upstream end connected to the manifold and having a downstream part having its downstream end connected to the corresponding injector, and means to compensate for the effect of said acceleration on the flow of fuel to the injectors comprising a valve device connected in each of said conduits, each of said valve devices comprising a chamber with an inlet orifice connected to the downstream end of the upstream part of the associated conduit and an outlet connected to the upstream end of the downstream part of the associated conduit, said inlet being at the end of said chamber towards which a component of said acceleration acts, and a weighted valve member freely slidable in said chamber towards and away from said inlet orifice, the direction of sliding of the said valve member being parallel to said component of acceleration, the valve member co-operating with the corresponding inlet orifice to restrict the flow therethrough when the system is subjected to said acceleration, the mass of the weighted valve member per unit area of the orifice being selected so that the force produced thereon by said component of acceleration per unit area of the orifice differs from the force produced on each of a plurality of the other weighted valve members by an amount equal to the product of the component of acceleration and a mass proportional to the head of fuel between the location of said injector and the location of the fuel injector associated with the other weighted valve member measured in a direction parallel to that of the component of acceleration, whereby the force opposes the pressure of the fuel in the conduit due to the action of the acceleration on the head of fuel.

6. A fuel system comprising an annular fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors spaced apart in the direction of an acceleration to which the system is subjected, a plurality of conduits connected to said manifold and leading to said fuel injectors, each conduit having an upstream part having its upstream end connected to the manifold and having a downstream part having its downstream end connected to the corresponding fuel injector, and means to compensate the fuel flows to said fuel injectors for variations in liquid head in said manifold due to said acceleration comprising a valve device'connected in each of said conduits, each of said valve devices comprising a chamber with an inlet orifice connected to the downstream end of the upstream part of the conduit and an outlet unobstructed at all times connected to the upstream end of the downstream part of the conduit, said inlet being at the end of said chamber towards which said acceleration acts, and a weighted valve member in said chamber freely slidable towards and away from the associated inlet orifice in a direction parallel to said acceleration and co-operating with said inlet orifice to restrict the flow therethrough when the system is subjected to said acceleration, the mass of each of a plurality of the weighted valve members per unit area of the respective orifice being selected to differ from each other weighted valve member by an amount directly 'proportional to the product of the fuel density and the spacing of the associated fuel injector from the fuel injector associated with the other weighted valve member measured in the direction of said acceleration.

7. A fuel system comprising a fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors located at different heights measured in a selected direction, a plurality of conduits connected to said manifold and leading to said fuel injectors, each conduit having an upstream part having its upstream end connected to the manifold and having a downstream part having its downstream end connected to the corresponding fuel injector, and means to compensate the fuel flows to said fuel injectors for variations in the liquid head in said manifold produced when the fuel system is subjected to an acceleration acting either in said selected direction or in the opposite direction relative to said fuel system comprising first and second valve de vices connected in flow series in each of said conduits, each said valve device comprising a chamber with an inlet orifice and with an outlet unobstructed at all times, the inlet orifice of the first valve device being connected to the downstream end of the upstream part of the conduit, the outlet of the second valve device being connected to the upstream end of the downstream part of the conduit, and the outlet of the first valve device being connected to the inlet of the second valve device, one of said inlets being at the end of its respective chamber towards which an acceleration in said selected direction acts and the other inlet being at the end of its respective chamber towards which an acceleration in said opposite direction acts, and a weighted valve member in each said chamber freely slidable towards and away from said inlet orifice, whereby the weighted valve member of each first valve device co-operates with the respective inlet orifice to restrict fiow therethrough when the system is subjected to an acceleration in said selected direction and the'weighted valve member of each second valve device co-operates with its respective inlet orifice to restrict flow therethrough when the system is subjected to an acceleration in said opposite direction, the mass of each weighted valve member of the first valve devices per unit area of the associated inlet orifice being selected to differ from the masses of the Weighted valve members of the other first valve devices by amounts each directly proportional to the product of the fuel density and proportional to the respective distances of the associated fuel injector from the fuel injectors associated with the other valve members measured in the selected direction, and the mass of the weighted valve member of each second valve device per unit area of its associated inlet orifice being selected to differ from the masses of the weighted valve members of the other second valve devices by amounts each directly proportional to the product of the fuel density and proportional to the respective distances of the associated injector from the fuel injectors associated with the other valve devices measured in said opposite direction.

8. A fuel system comprising a fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors located at different heights measured in a selected direction, a plurality of conduits connected to said manifold and leading to said fuel injectors, each conduit having an upstream part having its upstream end connected to the manifold and having a downstream part having its downstream end connected to the corresponding injector, and means to compensate the fuel flows to said fuel injectors for variations in the liquid head in said manifold produced by an acceleration or component of acceleration acting in one direction or in the opposite direction relative to said fuel system comprising a valve device connected in each of said conduits, each said valve device comprising first and second aligned chambers each with an inlet orifice connected to the downstream end of the upstream part of the conduit and an outlet connected to the upstream end of the downstream part of the conduit, said inlet orifice of the first chamber being at the end thereof towards which an acceleration or component of acceleration in said one direction acts, said chambers and said inlet orifices being aligned, and weighted valve means comprising a first weighted valve member in said first chamber and a second weighted valve member in said second chamber and a rigid connection therebetween, said Weighted valve members being freely slidable in said first and second chambers, and said first valve member co-operating with the inlet orifice of said first chamber to restrict flow therethrough and said second valve member simultaneously co-operating With the outlet of said second chamber to stop flow therethrough when said system is subjected to an acceleration or a component thereof acting in said one direction, and said second valve member co-operating with the inlet of said second valve chamber to restrict flow therethrough and said first valve member simultaneously co-operating with the outlet of said first chamber to stop flow therethrough when said system is subjected to an acceleration or component thereof acting in the opposite direction, t he mass of said. weighted valve means and the areas of each of the inlet orifices of the first said chambers being selected to give a mass per unit area of each inlet orifice of a first chamber which differs from those of the other valve devices by amounts directly proportional to fuel density and proportional to the respective distances of theassociated injector from the fuel injectors of the other valve devices measured in said one direction, and to give a mass per unit area of each inlet orifice of a second chamber which differs from those of the other valve devices by amounts directly proportional to the fuel density and proportional to the respective distances of the associated injector from the fuel injectors of the other valve devices measured in said opposite direction. a

9. A fuel system comprising an annular fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors located at points spaced apart around a circle coaxial with said manifold, a plurality of conduits connected to said manifold and leading to said fuel injectors, each conduit having an upstream part having its upstream end connected to the manifold and having a downstream part having its downstream end connected to the corresponding fuel injector and means to compensate the fuel flows to the fuel injectors for variations in the liquid head in said manifold due to an acceleration having a component acting in the plane of said circle of injectors and comprising a valve device in each of said conduits, each of said valve devices comprising a chamber with an inlet orifice connected to the downstream end of the upstream part of the conduit and an unobstructed outlet connected to the upstream end of the downstream part of the conduit, said inlet orifices being all of the same size, a weighted valve member in each chamber slidable towards and away from said inlet orifice along a line extending radially from the axis of said circle, a spring in each valve chamber urging said valve member in the radially-outward direction to close off the inlet orifice, said springs all having the same characteristics and each said weighted valve member having a mass per unit area of its associated inlet orifice equal to the product of the density of the fuel and the radius of the circle on which the fuel injectors are disposed.

10. A fuel system comprising an annular fuel supply manifold, a source of pressure fuel connected to said manifold, a plurality of fuel injectors located at points spaced apart around a circle coaxial with said manifold, a plurality of conduit means connected to said manifold and leading to said injectors, each conduit means having an upstream part having its upstream end connected to the manifold and having two downstream parts having their downstream ends each connected to an injector, and means to compensate the fuel flows to the fuel injectors for variations in the liquid head in the manifold due to an acceleration having a component acting in the plane of said circle of injectors and comprising a valve device in each of said conduit means, each of said valve devices comprising a chamber with an inlet orifice connected to the downstream end of the upstream part of the conduit means and two unobstructed outlets each connected, to the upstream end of one 'of the downstream parts of the conduit means, said inlet orifices being all of the same size, a weighted valve member in each chamber slidable towards and away from said inlet orifice along a line extending radially from the axis of said circle, a spring in each valve chamber urging said valve member in the radially-outward direction to close off the inlet orifice, said springs all having the same characteristics and each said weighted valve member having a mass per unit area of its associated inlet orifice equal to the product of the density of the fuel and'the radius of the circle on which the fuel injectors are disposed.

11. A fuel system for a gas turbine power plant having 7 a plurality of fuel nozzles at different vertical locations with respect to the power plant axis, and a valve associated with each nozzle for compensating for a difference in pressure head at the nozzles, each valve having a passage for the flow of fuel therethrough, a movable closure interposed in the passage and restricting fuel flow, and a seat for the closure defined by the passage walls, the masses of the closures being individually selected to regulate the fuel flow through'each valve so as to equalize the flows from the nozzles, and the mass per unit passage area of any one closure exceeding the mass per unit passage area of any other closure which is vertically higher than said one closure by an amount which is the product of the fuel density and the vertical distance between said one closure and said other closure.

12. A fuel system for a gas turbine power plant having a plurality of fuel nozzles, some at least of which are spaced apart in a direction transverse to the power plant axis, and a valve associated with each nozzle for compensating for a difference in pressure head at the nozzles caused by an acceleration acting in said direction, each valve having a passage for the flow of fuel therethrough, a movable closure interposed in the passage and restricting fuel flow, and a seat for the closure defined by the passage walls, each closure being of selected mass per unit area of the passage to regulate the fuel flow through the respective valve, the mass per unit passage area of the closure associated with a nozzle which is spaced apart from any other nozzle in the direction of action of said acceleration, exceeding the mass per unit passage area of the closure associated with said other nozzle by an amount equal to the product of the fuel density and the distance said nozzles are spaced apart in said direction.

References Cited in the file of this patent UNITED STATES PATENTS 

